Rebuild or replace vacuum petcock?

[LAB3]

Having owned a Suzuki GS series bike in the past one of the questions that often comes up is the vacuum petcock and it seems my newly acquired SX has the same issue. The GS crowd seems to pretty much be in agreement that it's difficult and really not worth while to try to rebuild a vacuum petcock since it rarely works as intended afterward and you're better off replacing it with a high quality one, NOS or equivalent, not a cheapy unit. My XS has the octopus removed with each petcock feeding two carbs which seems to work fine by me but one of them is no longer shutting off, it's "On" all the time. Personally I like the idea of keeping things a no-brainer and letting the vacuum do the job of shutting off the petcock but the price of going "Manual" is too hard to ignore so here are my questions: Is there a "best" method to rebuild these petcocks? Is it even worth trying? What is my best source if I decide to go with a new vacuum petcock? Thanks in advance!

[DiverRay]

I went to manual on my Special, after removing the Octy. It's a lot easier, and now that I have GOOD fuel line, it runs well. I don't remember who I bought them from, but I think it was an Ebay dealer. Remember, the Standard and Special are TWO DIFFERENT bolt patterns for the petcocks, so make sure you are getting the correct one for the tank you are using! I am running a Standard tank on my Special, so I have more of a range. I also have the Vetter fairing and box on it.

[jetmechmarty]

The vacuum fuel valve on my XS650 works just fine. I've had the bike for 39 years and never had a problem with it. I've had the Eleven Special since 2003, so someone else took care of it before me. The vacuum shutoff (octopus) stopped working as in failed to close. I rebuilt it and it has been doing fine for years. I think some of the kits come with an o'ring that has too small a cross section. That's easy enough to correct.

Here's a helpful link: Rebuilding the Yamaha Vacuum Fuel Valve w/pics

[LAB3]

Here's a helpful link: Rebuilding the Yamaha Vacuum Fuel Valve w/pics

I'd have never thought to polish up that sealing seat, clean yes, polish no. Thanks for the link!

[cajun31]

I have never owned a standard and have never had to rebuild or deal with the vacuum petcock. I have and always will keep the Octy on my specials. I like the idea when it is functioning properly that I have another safeguard against a flooded crankcase and spun bearings. I always shut off my petcocks when I park the bike though. Even if just going into a store they are shut off. Just a habit for me and I do that on all of my bikes that have carburetors.

[LAB3]

How do you shut off a vacuum petcock when it has no off position? Since you personally have never had a problem with a petcock does this mean that others automatically won't as well? If you where to have bought a bike three weeks ago with no octopus on it would you install one? Guess I'm trying to understand what you're adding to the conversation here....

[jetmechmarty]

How do you shut off a vacuum petcock when it has no off position? Since you personally have never had a problem with a petcock does this mean that others automatically won't as well? If you where to have bought a bike three weeks ago with no octopus on it would you install one? Guess I'm trying to understand what you're adding to the conversation here....

cajun31 has Specials. Specials have manual petcocks rather that the vacuum taps on the standard. The Special also has a single point vacuum shutoff valve (octy or spider valve) installed as a safety device. Speaking for myself, I would return the bike to stock if it were missing. I'm a fan of safety devices involving gasoline. Older bikes with manual taps have no such devices, so those familiar with bikes predating those devices often have no issue removing them, especially in the case of the Eleven Special that involves extra plumbing.

[cajun31]

cajun31 has Specials. Specials have manual petcocks rather that the vacuum taps on the standard. The Special also has a single point vacuum shutoff valve (octy or spider valve) installed as a safety device. Speaking for myself, I would return the bike to stock if it were missing. I'm a fan of safety devices involving gasoline. Older bikes with manual taps have no such devices, so those familiar with bikes predating those devices often have no issue removing them, especially in the case of the Eleven Special that involves extra plumbing.

thanks for clarifying for me Marty. I thought my opening comment would have indicated that, however, I probably assume too much. One other tidbit that I know I have read on here somewhere over time is that the vacuum petcocks can be modified to add an off position How to easily add an "off" to your standard's petcocks - XS11.club Forums

[jetmechmarty]

No dream. There’s a gate that can be filed off.